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Data Connectivity Integrating Process Data from Industrial Weighing Efficient transfer of weighing process data to higher level MES or ERP systems can help make manufacturing processes more transparent. Increased transparency can improve asset use, reduce operating costs, and make complying with certification standards or industrial regulations easier. However, identifying and implementing the most effective system for data collection and integration can be challenging, especially in a legacy manufacturing operation. This paper explores weighing process integration challenges and provides points to consider when defining operating boundaries and data objectives. Weighing and communication solutions are more likely to meet objectives and produce measurable ROI when these points are taken into account. Contents 1 Defining data integration challenges 2 Determining data integration objectives 3 Assessing data integration routes 4 Suggesting best practices 5 Troubleshooting communications 6Summary 7 Additional resources Data Connectivity 1Defining data integration challenges Challenges manufacturers face when effectively integrating weighing data into an automated ERP/MES system include: • Optimized hardware The ability to use solutions that integrate data from multiple scales into a single automated system. • Speed The ability to deliver reliable, “filtered” weighing data to a higher-level automation system during timesensitive applications (such as high precision filling) so production adjustments can be made. • Easy of upgrading Allowing for or replacing equipment with new controllers that improve automation and data access capabilities. • Flexibility The ability to communicate information that affects weighing accuracy, materials use and production rates such as product ID, target weight, tare weight, scale status, operator messages, and error information. • Adverse conditions High pressure wash-down; explosive/corrosive environments; high vibrations; electromagnetic interference and/or extreme temperatures. An expert assessment of the conditions in which a weighing system is expected to perform, without loss of accuracy or communications to the higher level system, can help define operating boundaries. 2Determining data integration objectives Before selecting a weighing terminal or communication system, an assessment of data integration objectives must be made. Typical questions to answer include: •What type of information will be communicated between the weighing terminal and automation system? •Who or what needs the data and why? •What triggers will be used to initiate data transfer, and how frequently will communication be made? •What are present data format requirements? Are those requirements flexible? •What is the current communication medium? Are there other viable options? •How might the data format requirements or the communication medium evolve in the foreseeable future? Several of these questions are strategic in nature: what type of information is required, by whom, and to what end? Once these questions have been answered, many options can be explored to meet, or potentially exceed the objectives. This pragmatic approach increases the likelihood that once implemented, the data integration solution will provide the best return on investment. 3Assessing data integration routes If PLC data integration is not required, PC-based serial or Ethernet TCP/IP data communication are viable options. In comparison to PLC-to-PC communication, lower cost Ethernet TCP/IP communication is feasible via widely available wired or wireless networking 2 METTLER TOLEDO - White Paper - Data Connectivity devices. However, special care should be taken when implementing Ethernet TCP/IP-based networks to ensure that mission-critical communication, data, and devices are adequately isolated from business networks. For more information, see Best Practices, below. © 2012 Mettler-Toledo AG Data Connectivity If PLC control is a prerequisite, the fieldbus chosen to support process requirements can have a significant impact on the data integration objectives as well as the project budget. The fieldbus assessment will determine the potential number of nodes, device types, and the data capacity vs. transfer rate. The fieldbus choice, in combination with the choice of terminal, will also determine weighing data-related capabilities as follows: • Upload of target weight data to the weighing terminal • Download of calibration information and/or calibration via a PLC program • Download scale monitoring statistics • Messaging options (cyclic, explicit, or both cyclic and explicit messaging) With the right combination of weighing terminal, fieldbus selection, and PLC system, all of the above capabilities are possible. A hybrid approach is also a viable option for achieving additional data integration objectives. A PLC connection is leveraged to manage a critical production process and simultaneously communicate data, as outlined above. In parallel to the PLC-to-terminal data exchange, an additional connection (via serial or Ethernet TCP/ IP) is implemented between the terminal and a PC to achieve additional data integration objectives. For instance, a hybrid approach might include • METTLER TOLEDO IND560 terminal including: ■ EtherNet/IP™ fieldbus option for communication with a RSLogix PLC EtherNet/IP™-based system ■ Optional COMM2 Ethernet TCP/IP card for communicating with a back-office PC In this scenario, the terminal-to-PC communication could support data integration to an OPC-compliant server. OPC provides a standardized data format that can lower integration and support costs, reduce system complexity, and speed up industrial automation project development. METTLER TOLEDO has partnered with Kepware, developers of KepServer EX to jointly facilitate delivery of mission-critical weighing data into an OPC-compliant environment. See the list of "additional resources" at the end of this whitepaper for a link to Kepware. Here is a comparison of data integration requirements and limitations via a few of the most common communication paths: Communication method Requirements/limitations Basic weighing data via 4-20mAor 0-10VDC signal • Limited communication of weight and/or rate • Separate communication between control system and weighing terminal for functions such as zero or print commands Basic weighing data via serial RS232/422 or Ethernet TCP/IP* • Standard terminal data format with pre-defined, limited data sets • “Print template” stored in weighing terminal and communicated to external hardware • Shared data server access via custom solutions Weighing data via PLC fieldbus, e.g. EtherNet/IP™, Profibus® DP • Requires PLC hardware/program to integrate data • PLC interface capabilities limit data packet/message size * NOTE: certain options outlined above are limited to specific terminals 3 METTLER TOLEDO - White Paper - Data Connectivity © 2012 Mettler-Toledo AG Data Connectivity 4 Suggesting best practices Best practices for integrating weighing terminals with higher level systems will follow automation equipment supplier recommendations. While best practices for every type of automation network is beyond the scope of this paper, several best practices examples for implementing ethernet-based networks such as EtherNet/IP™, Modbus TCP™ or ProfiNet® follow. Industrial Network vs. Office Network Industrial network design requires different considerations from office network design. Traffic on an office network, typically Ethernet TCP/IP-based, is non-deterministic, or not highly time-critical. In a production network during a manufacturing process, data exchange, consisting primarily of UDP/IP Unicast and Multicast packets, is highly time-critical. The cyclic portion of the traffic on an EtherNet/IP™ network is high-rate, shortpacket, continuous traffic that is deterministic or highly time-critical. TCP/IP-based cluster communications between weighing terminals is also time critical and must be adequately isolated from other network traffic. Conversely, if a Ethernet TCP/IP-based production network connected to a larger plant network, the continuous propagation of Multicast packets must be blocked. While the continuous information flow within the subnet may be desirable for optimizing weighing, it can cause a multicast message storm that degrades the plant’s overall network performance. Optimizing Industrial EtherNet/IP Rockwell Automation has provided the following recommendations to optimize network performance when using EtherNet/IP™. However, many of these recommendations can also be applied to any Ethernet fieldbus to optimize I/O performance. Select Unicast EtherNet/IP™ communication whenever possible. Unicast I/O for EtherNet/IP™ allows for direct point-to-point communication between two 4 METTLER TOLEDO - White Paper - Data Connectivity devices on a network. This communication is more efficient when I/O data does not need to be shared among multiple devices. Further information on Unicast vs. Multicast communication can be found in ODVA publication 70, “Recommended Functionality for EtherNet/IP™ Devices,” which can be accessed using this paper’s concluding links. Minimize device load due to unwanted IP multicast traffic. Depending on sub-net configuration and device connectivity, this objective can be achieved using managed Ethernet switches supporting virtual LANs (VLANs) and IP multicast routing. Minimize switch load due to unwanted IP multicast traffic. Use full duplex, managed industrial network switches capable of IGMP (Internet Group Multicast Protocol) snooping, port mirroring, VLAN set-up, SNMP statistical information, IP address blocking, auto-restore of configurations, per port broadcast/multicast storm control, spanning tree protocol, and frame prioritization. Minimize network load due to unwanted incoming IP multicast traffic. Block IP multicast traffic generated within the EtherNet/IP™ subnet from propagation into the larger plant network. Sweating the little stuff. Heat ratings, electrical noise, and grounding issues should be addressed with the appropriate solution. • Network cable connectors with IP67 environmental ratings and extended temperature ratings to 80°C are preferred when establishing industrial networks • CAT6 or CAT6a industrial-grade shielded cabling must be used in high noise environments • In some cases grounded metal conduit can minimize electrical interference. • Proper grounding can avoid loops that cause communication drops or signal interference. Don't reinvent the wheel. Use vendor-supplied PLC sample code or other integration tools such as Rockwell Automation Add-on-Profiles (AOPs) and Add-on-Instructions (AOIs) to simplify integrating devices into an automation network and minimize programming errors. © 2012 Mettler-Toledo AG Data Connectivity 4,000 3,500 3,000 2,500 2,000 1,500 1,000 Shipments of Industrial EthernetBased Devices (Thousands of Units) ©2008 ARC Advisory Group 500 0 2007 2008 2009 2010 2011 2012 5 Troubleshooting communications Data communication troubleshooting for a weighing terminal and automation system depends on the communication method being used. For serial or EtherNet TCP/IP to PC, simple connection using a PC application such as HyperTerminal can verify basic weight data transfer via the terminal’s communication port. Ethernet network troubleshooting is typically divided into these areas: • Network media (cabling, connectors, network interface cards) • Software settings/network configuration • Network signal performance A variety of technician tools such as TDR (time domain reflectometer) devices, handheld network analyzers, and cable performance analyzers are employed when troubleshooting network media problems. For PLC based applications, some vendors supply PC-based simulation software for viewing and verifying data communicated from a weighing terminal’s PLC port. LEDs mounted to the communication PCB provide basic information regarding operating status. Bypassing the PLC application program and directly writing to output command and data words can provide powerful troubleshooting as well. Weighing terminal troubleshooting can also occur via remote access to a terminal’s configuration file, error logs, and web pages showing diagnostics or operational status. METTLER TOLEDO IND560 Weighing Terminals 5 METTLER TOLEDO - White Paper - Data Connectivity © 2012 Mettler-Toledo AG Data Connectivity 6Summary Efficient transfer of process data to higher level MES or ERP systems along with intelligent weighing platform/ system upgrades can: •Enhance manufacturing process controls •Improve asset use •Lower operating costs •Generate measurable ROI Clear goal identification – either performed internally, or with the help of weighing process specialists – can ensure that hardware and software investments reap intended process improvement dividends. Considerations for proposed system upgrades include: •Speed of process (for example, high-speed filling), which influences data exchange rates •Existing equipment and potential connectivity •Available budget •Adverse operating conditions, such as high-pressure washdown, corrosive chemicals, extreme temperature, electrical noise, and grounding •The data itself – who/what needs it, why, and in what format? •Is PLC connectivity is required, or will serial or Ethernet connectivity work? Ethernet network troubleshooting requires knowledge of network media, configuration, and signal performance. Some vendors supply PC-based simulation software for verifying data communicated from a weighing terminal’s PLC port. Vendors themselves can help with comparisons of various weighing platform and system communication solutions. 7 Additional resources More information on communication capabilities, data format, and fieldbus network-specific requirements for METTLER TOLEDO weighing terminals are available via – www.mt.com/ind-process-data-integration. •METTLER TOLEDO Terminals – www.mt.com/terminals •Rockwell Automation Integrated Architecture Tools – www.rockwellautomation.com/solutions/integratedarchitecture/resources4.html#Termination •Rockwell Integrated Architecture Builder software – www.rockwellautomation.com/en/e-tools/configuration.html •ODVA DeviceNet™ Library – www.odva.org/default.aspx? tabid=73 •ODVA EtherNet/IP™ Library – www.odva.org/default.aspx? tabid=76 •Profibus/ProfiNet® – www.profibus.com •Network Analyzer Wire Shark – www.wireshark.org •Fluke Networks – www.flukenetworks.com •Kepware/KepServerEX (OPC) – www.kepware.com Mettler-Toledo AG Industrial CH 8606 Greifensee Switzerland Phone +41-44-944 22 11 Fax +41-44-944 30 60 Subject to technical changes © 04/2012 Mettler-Toledo AG www.mt.com/terminals For more information